(1) Field of the Invention
This invention relates to recorders and, more particularly, to ink jet recorders in which droplets of ink are projected through an orifice onto a receiving print medium.
(2) Description of the Prior Art
U.S. Pat. No. 3,886,564 to Naylor et al discloses an ink jet printing system in which the velocity of an ink jet stream is detected and which responds to the detected velocity. A velocity signal is derived which is then compared to a reference signal, with the resulting comparison being applied to a logic circuit which controls the application of an information signal to the charge electrode structure.
U.S. Pat. No. 3,907,429 to Kuhn et al discloses an ink jet printing system in which a direct velocity measurement of the droplets in an ink stream is achieved through utilizing a strobe light source and passing the stream of droplets between the strobe light source and a pair of apertures with light detecting means therebehind. Depending upon the distance between the apertures, various means are employed for determining the velocity of the droplets in accordance with the relation of the droplets to the apertures during the strobing of the light source.
U.S. Pat. No. 3,911,445 of Foster discloses an ink jet printing system in which the time a droplet arrives at a given position is sensed for providing a position signal which is compared with a reference signal indicative of when the given droplet is supposed to arrive at the given position. In response to a discrepancy between the position signal and the reference signal, an alarm indication is manifested, and a phase correction is made relative to drop excitation and drop charging.
The prior art discussed teaches use of sensed variations in velocity of an ink jet stream to determine the time when an information signal is to be applied to a charge electrode to effect printing. However, the above prior art does not teach the measurement of variations in velocity from stream-to-stream in a multi-jet printer, nor does it teach use of such data to determine the difference between the slowest stream velocity and the velocity of each of the other streams to effect the delayed application of an information imparting signal to the corresponding charge electrode. In addition, the prior art does not teach provision of data and correction registers to control an information imparting output register.